[flang][omp] Emit omp.workshare in frontend (llvm#101444)

Emit the contents of OpenMP workshare constructs in `omp.workshare`.

Author: ivanradanov

flang/lib/Lower/OpenMP/OpenMP.cpp

@@ -1372,6 +1372,15 @@ static void genTaskwaitClauses(lower::AbstractConverter &converter,
       loc, llvm::omp::Directive::OMPD_taskwait);
 }
 
+static void genWorkshareClauses(lower::AbstractConverter &converter,
+                                semantics::SemanticsContext &semaCtx,
+                                lower::StatementContext &stmtCtx,
+                                const List<Clause> &clauses, mlir::Location loc,
+                                mlir::omp::WorkshareOperands &clauseOps) {
+  ClauseProcessor cp(converter, semaCtx, clauses);
+  cp.processNowait(clauseOps);
+}
+
 static void genTeamsClauses(lower::AbstractConverter &converter,
                             semantics::SemanticsContext &semaCtx,
                             lower::StatementContext &stmtCtx,
@@ -2033,6 +2042,24 @@ genTaskyieldOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
   return converter.getFirOpBuilder().create<mlir::omp::TaskyieldOp>(loc);
 }
 
+static mlir::omp::WorkshareOp
+genWorkshareOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
+               semantics::SemanticsContext &semaCtx,
+               lower::pft::Evaluation &eval, mlir::Location loc,
+               const ConstructQueue &queue,
+               ConstructQueue::const_iterator item) {
+  lower::StatementContext stmtCtx;
+  mlir::omp::WorkshareOperands clauseOps;
+  genWorkshareClauses(converter, semaCtx, stmtCtx, item->clauses, loc,
+                      clauseOps);
+
+  return genOpWithBody<mlir::omp::WorkshareOp>(
+      OpWithBodyGenInfo(converter, symTable, semaCtx, loc, eval,
+                        llvm::omp::Directive::OMPD_workshare)
+          .setClauses(&item->clauses),
+      queue, item, clauseOps);
+}
+
 static mlir::omp::TeamsOp
 genTeamsOp(lower::AbstractConverter &converter, lower::SymMap &symTable,
            semantics::SemanticsContext &semaCtx, lower::pft::Evaluation &eval,
@@ -2631,10 +2658,7 @@ static void genOMPDispatch(lower::AbstractConverter &converter,
                   llvm::omp::getOpenMPDirectiveName(dir) + ")");
   // case llvm::omp::Directive::OMPD_workdistribute:
   case llvm::omp::Directive::OMPD_workshare:
-    // FIXME: Workshare is not a commonly used OpenMP construct, an
-    // implementation for this feature will come later. For the codes
-    // that use this construct, add a single construct for now.
-    genSingleOp(converter, symTable, semaCtx, eval, loc, queue, item);
+    genWorkshareOp(converter, symTable, semaCtx, eval, loc, queue, item);
     break;
   default:
     // Combined and composite constructs should have been split into a sequence

flang/test/Lower/OpenMP/workshare.f90

@@ -6,7 +6,7 @@ subroutine sb1(arr)
   integer :: arr(:)
 !CHECK: omp.parallel  {
   !$omp parallel
-!CHECK: omp.single  {
+!CHECK: omp.workshare {
   !$omp workshare
     arr = 0
   !$omp end workshare
@@ -20,7 +20,7 @@ subroutine sb2(arr)
   integer :: arr(:)
 !CHECK: omp.parallel  {
   !$omp parallel
-!CHECK: omp.single nowait {
+!CHECK: omp.workshare nowait {
   !$omp workshare
     arr = 0
   !$omp end workshare nowait
@@ -33,7 +33,7 @@ subroutine sb2(arr)
 subroutine sb3(arr)
   integer :: arr(:)
 !CHECK: omp.parallel  {
-!CHECK: omp.single  {
+!CHECK: omp.workshare  {
   !$omp parallel workshare
     arr = 0
   !$omp end parallel workshare